Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS AND METHODS FOR RESTRICTING FLOW IN A BORE
FIELD OF THE INVENTION
The invention relates to a wellbore valve and in particular, but not
exclusively, to
a wireline valve for sealing a wellbore. The invention also relates to methods
of sealing
a wellbore.
BACKGROUND OF THE INVENTION
Wellbores for accessing oil and gas reserves are typically provided with one
or
more valves or pairs of valves for restricting the wellbore. These valves are
used to
resist the flow of fluids in the bore and may ultimately be used to close the
wellbore,
such as BOPs. The valves are used to prevent undesirable exposure of
pressurised
fluids during the drilling or operation of a well. For example, in a downhole
intervention
operation, wireline valves allow the well operator to insert and remove tools
deployed
on coiled tubing or wireline within a wellbore while maintaining pressure in
the well.
Wireline valves are intended to stop the flow of a fluid through a tubular or
to
seal an annular space between two tubulars. Different types of wireline
valves, such as
annular or blind, are available. For example, blind valves crush or shear
tubulars then
seal the wellbore.
The valve often comprises a pair of seals that are pressed against each other
to
prevent fluid flowing through the bore. A valve sometimes has a cutter for
shearing
equipment such as piping or wireline that may be located in the bore to allow
the valve
to close to seal off the wellbore.
Wireline valves generally require movement of parts into a pressurised fluid
in
the wellbore. The valves are usually hydraulically activated, although some
valves are
mechanically activated.
In order to seal the bore, valve actuators must move parts that are exposed to
the wellbore fluid pressure. Fluid pressure in wells can easily exceed 50 MPa
and the
resultant forces on parts of the valve are typically several tons.
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SUMMARY OF THE INVENTION
According to an aspect of the invention there is provided an apparatus for
restricting a flow of fluid through a bore, the apparatus comprising:
a bore sealing member; and
an actuation assembly for moving the bore sealing member between a first
configuration corresponding to a bore open configuration and a second
configuration
corresponding to a bore closed configuration, the actuation assembly
comprising an
activation member with a first end portion and a second end portion, wherein
the actuation
assembly is configured to isolate the first and second end portions of the
activation
member from a bore fluid; and
wherein the apparatus is configured to displace substantially the same volume
of
fluid in the bore in the first configuration and in the second configuration.
Isolating the first end portion and the second end portion of the activation
member
from a bore fluid enables the activation member to move between a first
position
corresponding to the first configuration and a second position corresponding
the second
configuration, without pressure associated with a bore fluid acting on an end
portion of the
activation member; such as to resist movement of the activation member between
the first
position and the second position.
The first configuration may be a wellbore open configuration.
The second configuration may be a wellbore closed configuration.
As noted above, the apparatus may be configured to displace substantially the
same volume of fluid in the first configuration and in the second
configuration. The total
volume of fluid displaced by the apparatus may be the same in the first
configuration and
in the second configuration. The displaced volume of fluid may be a static
volume of fluid.
Movement of the apparatus between the first and second configurations may not
affect the
displaced volume of fluid. Maintaining the same volume of fluid displaced by
the apparatus
in the first configuration and in the second configuration ensures that force
is not required
to displace additional fluid when the apparatus is moved between the first and
second
configurations.
Alternatively, the apparatus may be configured to displace a different volume
of
fluid in the second configuration than in the first configuration. For
example, the apparatus
may be configured to displace a greater volume of fluid in the second
configuration.
Displacing a greater volume of fluid in the second configuration may bias the
apparatus
towards the first configuration. Alternatively, the apparatus may be
configured to displace
a greater volume of fluid in the first configuration; for example to bias the
apparatus
towards the second configuration.
The apparatus may be biased towards the first configuration. Alternatively,
the
apparatus may be biased towards the second configuration.
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The apparatus may be configured to occupy substantially the same volume
within a wellbore fluid envelope in the first configuration and in the second
configuration.
The first end portion of the activation member may be configured to be
proximal
to the bore in the first configuration and the second end portion of the
activation
member may be configured to be distal to the bore in the first configuration.
The actuation assembly may be configured to move the activation member in a
direction substantially perpendicular to the bore.
The actuation assembly may further comprise an isolator comprising a first
side
configured for receiving the first end portion of the activation member. The
actuation
assembly may be configured to define an isolation chamber between the first
end
portion of the activation member and a portion of the isolator.
The actuation assembly may be configured to separate the isolator first side
from the bore fluid and to position an isolator second side in fluid
communication with
the bore fluid. The isolator may be configured to form a boundary between a
first
portion of the apparatus and a second portion of the apparatus, the first
portion of the
apparatus configured to be exposed to wellbore fluid pressure and the second
portion
of the apparatus configured to be exposed to a second fluid pressure. The
second fluid
pressure may be lower than the wellbore fluid pressure, for example the second
fluid
pressure may be atmospheric.
The actuation assembly may further comprise a first end portion seal, the
first
end portion seal configured to prevent the first end portion contacting the
bore fluid. For
example, to prevent bore fluid entering the isolation chamber.
The first end portion seal may be an annular seal between the activation
member and the isolator.
The first end portion and the second end portion of the activation member may
be configured to be in fluid communication. For example, the first end portion
of the
activation member may be linked to the second end portion of the activation
member
via a fluid passage, such as a conduit. Alternatively, the first end portion
and the
second end portion may be isolated such that the first end portion and second
end
portions may be subjected to different fluid pressures.
The isolator may be configured to accommodate a stroke of the activation
member. For example, the isolator may be a cylinder.
The activation member may be a piston.
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The isolator may be configured to maintain substantially the same position
relative to the bore during movement of the activation member from the first
position to
the second position. For example the isolator may be fixed.
The activation member may further comprise a bore sealing member interface.
The bore sealing member interface may be located between the first end portion
and
the second end portion of the activation member.
The activation member may comprise a central portion located between the first
and second end portions. The central portion may be configured to be in fluid
communication with the bore fluid. Alternatively, the central portion may be
configured
to be isolated from the bore fluid.
The actuation assembly may further comprise an activation member housing
configured for receiving the central portion.
The isolator may be attached to the activation member housing. For example,
the activation member housing may comprise the isolator.
The isolator may be configured to control the bore fluid pressure acting
axially
on the activation member.
The activation member housing may comprise a first portion and a second
portion, the first portion configured to be in fluid communication with the
bore fluid and
the second portion configured to be isolated from the bore fluid.
The actuation assembly may further comprise a proximal chamber, the proximal
chamber located between the isolator and the activation member housing. The
actuation assembly may be configured to enable fluid communication between the
proximal chamber and the bore. Additionally or alternatively, the actuation
assembly
may be configured to isolate the proximal chamber from fluid in the bore.
The actuation assembly may further comprise an intermediate chamber. The
intermediate chamber may be separated from the proximal chamber by the
activation
member housing. The intermediate chamber may be located between the proximal
chamber and the second end portion of the activation member.
The actuation assembly may further comprise a second end portion seal. The
second end portion seal may be configured to prevent the second end portion
contacting the bore fluid. For example, the intermediate chamber may be
fluidly
isolated from the proximal chamber.
The first end portion seal may be configured to seal a first cross-sectional
area
of the activation member perpendicular to the direction of extension. The
second end
portion seal may be configured to seal a second cross-sectional area of the
activation
member perpendicular to the direction of extension. The first and the second
cross-
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sectional areas may be substantially the same. Alternatively, the second cross-
sectional area may be greater than the first cross-sectional area. For
example, the
second end portion seal may comprise an opening for receiving a larger
activation
member diameter than an opening of the first end portion seal. Alternatively,
the first
5 cross-sectional area may be greater than the second cross-sectional area.
The first and second cross-sectional areas may be selected according to a
wellbore fluid characteristic/s and/or a wellbore characteristic/s and/or a
desired force/s
required to move the bore sealing member between the first and second
configurations. For example, where the second end portion seal diameter is
greater
than a first end portion seal diameter, the difference between the diameters
may be
less for a larger fluid pressure.
The second end portion seal may be an annular seal between the central
portion and the activation member housing.
The activation member may be configured to move axially within the activation
member housing.
The actuation assembly may further comprise an activation member housing
seal between the intermediate chamber and the proximal chamber.
The actuation assembly may be housed in an actuation assembly casing. The
activation member housing seal may be located between the activation member
housing and the casing.
The intermediate chamber may be in fluid communication with the isolation
chamber, For example, the second intermediate chamber may be connected to the
isolation chamber via a fluid conduit.
The isolation chamber may be in atmospheric fluid communication. For
example, the isolation chamber may be fluidly connected, such as via a venting
conduit, to outside of the apparatus. The activation member may comprise at
least a
portion of the venting conduit. For example, the activation member may
comprise an
axial passage.
The actuation assembly may further comprise a distal chamber. The distal
chamber may be located between the intermediate chamber and the second end
portion.
The apparatus may be configured to be hydraulically activated. For example,
the distal chamber may be may be an activation chamber configured to be in
fluid
communication with a hydraulic source. Additionally, or alternatively, the
apparatus
may comprise a mechanical actuator. For example, the distal chamber may
comprise a
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first threaded member. The first threaded member may be configured to receive
a
second threaded member.
The mechanical actuator may be configured to maintain the bore sealing
member in the second configuration. For example, the mechanical actuator may
be a
manual lock.
The first threaded member may be configured to be located at a fixed distance
from the bore. The first threaded member may be configured to rotate about a
rotation
axis substantially perpend portionicular to the bore.
Axial movement of the first threaded member with respect to the second
threaded member may be restricted, such that rotational movement of the first
threaded member with respect to the second threaded member results in axial
movement of the first threaded member with respect to the second threaded
member.
The second threaded member may be configured to move the activation
member. For example a proximal end portion of the second threaded member may
contact a portion of the activation member proximal to the second end portion
of the
activation member.
The apparatus may be configured to define the rotational movement of the
activation member about an axis parallel to the direction of extension of the
activation
member. The actuation assembly may be configured to prevent rotation of the
activation member about the axis parallel to the direction of extension of the
activation
member. For example, the activation member may comprise a linear element. The
linear element may be a slot. Additionally, or alternatively the linear
element may be a
radial protrusion.
The bore sealing member interface may be configured to connect the central
portion to a bore sealing member support.
The bore sealing member support may be configured to move coaxially with the
activation member. The bore sealing member support may be configured to move
simultaneously with the activation member.
The bore sealing member interface may be configured to restrict movement of
the bore sealing member support relative to the activation member. For
example, the
bore sealing member interface may be configured to restrict rotation of the
bore sealing
member support. Additionally, or alternatively, the bore sealing member
interface.
At least a portion of the bore sealing member support may be configured to
substantially surround the isolator. For example, the bore sealing member
support may
be a sleeve.
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The bore sealing member support may be configured to define the rotational
movement of the bore seal about the axis parallel to the direction of
extension of the
activation member. The bore sealing member support may be configured to
prevent
rotation of the bore seal about an axis parallel to the direction of extension
of the
activation member. For example, the bore sealing member may comprise a
profiled
portion, the profiled portion configured to restrict circumferential movement
of the bore
sealing member.
The apparatus may further comprise a locking member. The locking member
may be configured to maintain the bore sealing member in the second
configuration.
For example, the locking member may be configured to engage the activation
member
in the second position such that axial movement of the activation member is
restricted.
The apparatus may comprise a wireline valve.
The apparatus may comprise a BOP.
The apparatus may comprise a gate valve.
The apparatus may be configured to expose only an intermediate portion of the
activation member to the bore fluid pressure, the intermediate portion located
between
the first and second end portions.
According to an aspect of the invention there is provided a method of
restricting
fluid flow in a bore, the method comprising:
moving a bore sealing member from a first configuration to a second
configuration by moving an activation member from a first position to a second
position,
the activation member comprising a first end portion and a second end portion,
wherein
the activation member is moved from the first position to the second position
with the
first end portion and the second end portion isolated from a bore fluid.
According to an aspect of the invention, there is provided an apparatus for
restricting a flow of fluid through a bore, the apparatus comprising
a bore sealing member; and
an actuation assembly;
wherein the bore sealing member is connected to the actuation assembly by a
profiled head, the profiled head being rotationally asymmetrical about a
central
longitudinal axis of the bore sealing member.
Providing such a profiled head prevents rotation of the bore sealing member
about its longitudinal axis such that an orientation of the bore sealing
member may be
maintained, such as an upright orientation relative to a wellbore.
The invention includes one or more corresponding aspects, embodiments or
features in isolation or in various combinations whether or not specifically
stated
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(including claimed) in that combination or in isolation. For example, it will
readily be
appreciated that features recited as optional with respect to one aspect may
be
additionally applicable with respect to any of the other aspects, without the
need to
explicitly and unnecessarily list those various combinations and permutations
here.
The above summary is intended to be merely exemplary and non-limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other aspects of the present invention will now be described, by way
of example, with reference to the accompanying drawings, in which:
Figure 1 is a sectional view of an existing wireline valve;
Figure 2 is a sectional view of a part of a wireline valve in accordance with
an
embodiment of the present invention, the sectional view corresponding to line
B-B of
Figure 5;
Figure 3 is a sectional view of the part of a wireline valve of Figure 2
showing
the wireline valve in a first open configuration;
Figure 4 is a sectional view of the part of a wireline valve of Figure 2
showing
the wireline valve in a first closed configuration; and
Figure 5 is a sectional view of the part of a wireline valve of Figure 2
showing
the wireline valve in a second closed configuration.
DETAILED DESCRIPTION OF THE DRAWINGS
Reference is first made to Figure 1 of the drawings, which is a sectional view
of
a conventional wireline valve, such as supplied by the applicant. The wireline
valve 10
shown is a ram wireline valve comprising a pair of sealing heads 12a, 12b for
sealing a
wellbore 14 to restrict the passage of fluid 16 through the wellbore. The
wireline valve
10 is shown in a partially closed configuration, with a first sealing head 12a
in an open
position and a second sealing head 12b in a closed position. Each sealing head
12a,
12b is attached to an activation rod 18a, 18b. A first activation rod 18a is
shown in a
retracted position, with the first sealing head 12a located proximal to a
first rod housing
20a; whilst a second activation rod 18b is shown in an extended position, with
the
second sealing head 12b distal to a second rod housing 20b.
Annular activation rod seals 22a, 22b are located between the respective first
and second activation rods 18a, 18b and their respective rod housing 20a, 20b.
The
annular activation rod seals 22a, 22b isolate sealing head chambers 24a, 24b
from rod
housing chambers 26a, 26b such that the sealing head chambers 24a, 24b are in
fluid
communication with the wellbore fluid 16 whilst the rod housing chambers 26a,
26b are
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isolated from the wellbore fluid 16 and therefore not subject to a wellbore
fluid 16
pressure.
Each activation rod 18a, 18b is attached to a respective threaded sleeve 28a,
28b, which in turn is connected to a respective screw 30a, 30b. Each screw
30a, 30b is
housed in a screw casing 32a, 32b such that the axial position of each screw
30a, 30b
is fixed with respect to the bore 14. Each screw 30a, 30b is operable by a
handle 34a,
34b such that each screw 30a, 30b rotates in the screw casing 32a, 32b. The
screwthread interface between each screw 30a, 30b and the respective threaded
sleeve 28a, 28b and a rotational restriction on each sleeve 28a, 28b results
in axial
movement of each sleeve 28a, 28b when the respective screw 30a, 30b is
rotated.
Axial movement of each sleeve 28a, 28b results in axial movement of the
respective
sealing head 12a, 12b such that the wellbore 14 can effectively be selectively
opened
or closed to the passage of fluid 16 through the wellbore 14.
Movement of an open sealing head 12a to the position of a closed sealing head
12b requires the displacement of a volume of fluid 16 in the wellbore
corresponding to
the additional volume of the rod 18a, 18b that enters the respective sealing
head
chamber 24a, 24b. The displacement of fluid 16 under wellbore pressure
requires
work. The pressure of the wellbore fluid 16 acting on the cross-sectional area
of the rod
18a, 18b perpendicular to the direction of extension requires a force, which
may be
several tons depending on the particular wellbore pressure and the diameter of
the rod
18a, 18b.
Each sealing head 12a, 12b comprises an aperture 36a, 36b for receiving a pin
38a, 38b; each pin 38a, 38b attached to the respective rod housing 20a, 20b.
Each
aperture 36a, 36b and corresponding pin 38a, 38b is offset from a central axis
of
extension 39a, 39b of each activation member 18a, 18b such that rotation of
each
sealing head 12a, 12b about each axis of extension 39a, 39b is prevented.
Reference is now made to Figures 2, 3, 4 and 5 of the drawings, which
illustrate
a part of a wireline valve 40 in accordance with an embodiment of the present
invention. As will be described, the wireline valve 40 is configured to be
moved
between an open configuration and a closed configuration in a wellbore 42 by
an
activation stem 44 with an activation stem first end portion 46 and an
activation stem
second end portion 48 isolated from a bore fluid 50, such that a wellbore
fluid 50
pressure does not act against the movement between the first and second
configurations.
The illustrated wireline valve 40 comprises a sealing head 52 attached to a
seal
sleeve 54. The seal sleeve 54 is cylindrical and comprises a first and a
second profiled
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portion 56a, 56b as can best be seen in Figure 2. The two profiled portions
56a, 56b
abut corresponding first and second sealing head profiled portions 58a, 58b.
In the
embodiment shown the profiled portion 56a, 56b is a flat portion. The profiled
portions
56a, 56b, 58a, 58b ensure that the sealing head 52 cannot rotate relative to
the seal
5 sleeve 54, about a longitudinal axis 60.
The seal sleeve 54 is connected to the activation stem 44 by a set of keys
62a.
The wireline valve 40 is configured to locate the seal sleeve 54 fully in the
wellbore fluid
50 such that no static fluid pressure difference acts across the seal sleeve.
The set of
keys 62a are attached to the activation stem 44 at a central portion 64. In
the
10 embodiment shown the keys 62a have axial apertures, allowing the passage
of fluid in
a proximal chamber 66 that houses the seal sleeve 54.
In the embodiment shown, the central portion 64 comprises a shoulder joining
two cylindrical portions of activation stem 44 of different diameters.
The activation stem 44 is received in a cylinder 68, with a cylinder seal 70
separating a cylinder chamber 72 from the proximal chamber 66 such that the
cylinder
chamber 72 is isolated from the wellbore fluid 50 pressure. The activation
stem first
end portion 46 is located in the proximal chamber 66 in the open configuration
as
shown in Figure 3 and also located in the proximal chamber 66 in the closed
configurations of Figures 4 and 5. The activation stem first end portion 46 is
thus
always separated from the wellbore fluid 50 by the cylinder seal 70 such that
the
activation stem first end portion 46 is never exposed to the wellbore fluid 50
pressure.
The cylinder 68 is connected to an activation stem housing 74 via supports
comprising axial slots 76 to allow the passage of the keys 62a from the first
configuration of Figure 3 to the second configurations of Figures 4 and 5. The
activation stem housing 74 comprises an activation stem seal 78 separating an
intermediate chamber 80 from the proximal chamber 66 such that the
intermediate
chamber 80 is isolated from the wellbore fluid 50 pressure. The activation
stem second
end portion 48 is also separated from the proximal chamber 66 by the
activation stem
seal 78, such that the activation stem second end portion 48 is isolated from
the
wellbore fluid 50 pressure. The activation stem second end portion 48 is thus
always
separated from the wellbore fluid 50 by the activation stem seal 78 such that
the
activation stem second end portion 48 is never exposed to the wellbore fluid
50
pressure, either in the positions of the open configuration as shown in Figure
3 or the
closed configurations of Figures 4 and 5, or positions therebetween.
In the embodiment shown, the diameter of the activation stem 44 at the
cylinder
seal 70 is less than the diameter of the activation stem 44 at the activation
stem seal
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78 in both the open and the closed configurations. The central portion 64
comprises a
transition from a first end portion 46 diameter to a second end portion 48
diameter,
such that the cylinder seal 70 receives a first cylindrical portion of
activation stem 44 of
lesser diameter than a second cylindrical portion received by the activation
stem seal
78.
In the embodiment shown, the activation stem housing 74 is attached to a
wireline valve casing 82 with a housing seal 84 preventing the passage of the
wellbore
fluid 50 in the annulus between the housing 74 and the casing 82. The housing
74
further comprises vents 86a fluidly connecting the cylinder chamber 72 through
an
annular passage 88 to the exterior of the casing 82, via the intermediate
chamber 80,
radial passages 89a and an axial passage 90 in the activation stem 74.
The intermediate chamber 80 is separated from a retraction chamber 92 via an
intermediate seal 94. The retraction chamber 92 is connected via a retraction
port 96 to
a first hydraulic source. The retraction chamber 92 is separated from an
extension
chamber 98 by a hydraulic seal 100. The extension chamber 98 is connected to a
second hydraulic source via an extension port 102.
In the open configuration of Figure 3, the activation stem 44 is in a
retracted
position. To move the wireline valve 40 from the open configuration of Figure
3 to the
closed configuration of Figure 4, pressure is applied to the extension chamber
98 by
the supply of hydraulic fluid through the extension port 102, such that a
pressure is
applied on an outer axial surface 91 of the second end portion 48 of the
activation stem
44. The axial force acting inwardly on the second end portion 48 exceeds the
axial
force acting outwardly on the first end portion 46 and frictional resistances
such that the
activation stem 44 moves towards the bore 42. To move the wireline valve 40
from the
closed configuration of Figure 4 to the open configuration of Figure 3,
pressure is
applied to the retraction chamber 92 by the supply of hydraulic fluid through
the
retraction port 96, such that a pressure is applied on an inner axial surface
93 of the
second end portion 48 of the activation stem 44. Hydraulic fluid is also
extracted from
the extension chamber 98 through the extension port 102.
Figure 5 shows an alternative closed configuration of the wireline valve 40 of
Figure 2. To move the activation stem 44 from the open position of Figure 3 to
the
closed position of Figure 5, mechanical force is applied to the second end
portion 48 by
rotating a handle 104. Rotation of the handle 104 causes a screw 106 to
rotate, the
axial position of the screw 106 relative to the bore 42 being restricted by
the casing 82
such that the screw 106 maintains the same axial position during rotation. The
screw
106 is connected by screwthread to a threaded sleeve 108, the rotational
movement of
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the threaded sleeve restricted by the activation stem 44 such that rotation of
the screw
106 results in axial movement of the threaded sleeve 108. The axial movement
of the
threaded sleeve 108 thus causes axial movement of the activation stem 44 such
that
the wireline valve 40 is moved to the closed configuration of Figure 5.
Mechanical
movement of the activation stem 44 by the handle 104 may be aided by a
pressure in
the activation chamber 98.
The closed configuration of Figure 5 may also be used subsequent to the
configuration of Figure 4. For example, hydraulic fluid may be used to rapidly
move the
valve 40 to the closed configuration and thereafter the screw 106 may be
rotated to
position the threaded sleeve 108 to act as a mechanical lock to prevent
movement of
the valve 40 to the first configuration under wellbore fluid pressure. Supply
of hydraulic
fluid to the extension chamber 98 may be stopped, the sleeve 108 maintaining
the
valve in the closed configuration of Figure 5. In the embodiment shown, as the
diameter of the activation stem seal 78 is greater than the diameter of the
cylinder seal
70, rotating the screw 106 in an opposite direction to return the threaded
sleeve 108 to
the position of Figure 4 is sufficient to move the valve 40 to the open
configuration of
Figure 3; provided that there is no significant pressure difference between
the
extension 98 and retraction 92 chambers.
Figure 5 further shows the section line B-B indicating the sectional view
depicted in Figure 2.
In an alternative embodiment the retraction port may be connected to the
cylinder chamber 72. For example, where there is no intermediate chamber 80
and the
axial passage 90 extends to the retraction chamber.
It will be apparent to those of skill in the art that the above described
embodiment is merely exemplary of the present invention, and that various
modifications and improvements may be made thereto, without departing from the
scope of the invention.
